Kernel: Steer away from heap allocations for ProcFS process data

Instead, use more static patterns to acquire that sort of data.

1 files changed, 205 insertions, 512 deletions

diff --git a/Kernel/ProcessSpecificExposed.cpp b/Kernel/ProcessSpecificExposed.cpp
index 3cf220cd7c..6e53a85f1c 100644
--- a/Kernel/ProcessSpecificExposed.cpp
+++ b/Kernel/ProcessSpecificExposed.cpp
@@ -9,601 +9,294 @@
 #include <AK/JsonValue.h>
 #include <Kernel/Arch/x86/InterruptDisabler.h>
 #include <Kernel/FileSystem/Custody.h>
+#include <Kernel/FileSystem/ProcFS.h>
 #include <Kernel/KBufferBuilder.h>
 #include <Kernel/Memory/AnonymousVMObject.h>
 #include <Kernel/Memory/MemoryManager.h>
+#include <Kernel/Process.h>
 #include <Kernel/ProcessExposed.h>
 
 namespace Kernel {
 
-class ProcFSProcessStacks;
-class ProcFSThreadStack final : public ProcFSProcessInformation {
-public:
-    // Note: We pass const ProcFSProcessStacks& to enforce creation with this type of directory
-    static NonnullRefPtr<ProcFSThreadStack> create(const ProcFSProcessDirectory& process_directory, const ProcFSProcessStacks&, const Thread& thread)
-    {
-        return adopt_ref(*new (nothrow) ProcFSThreadStack(process_directory, thread));
-    }
-
-private:
-    explicit ProcFSThreadStack(const ProcFSProcessDirectory& process_directory, const Thread& thread)
-        : ProcFSProcessInformation(String::formatted("{}", thread.tid()), process_directory)
-        , m_associated_thread(thread)
-    {
-    }
-    virtual bool output(KBufferBuilder& builder) override
-    {
-        JsonArraySerializer array { builder };
-        bool show_kernel_addresses = Process::current()->is_superuser();
-        bool kernel_address_added = false;
-        for (auto address : Processor::capture_stack_trace(*m_associated_thread, 1024)) {
-            if (!show_kernel_addresses && !Memory::is_user_address(VirtualAddress { address })) {
-                if (kernel_address_added)
-                    continue;
-                address = 0xdeadc0de;
-                kernel_address_added = true;
-            }
-            array.add(address);
+KResultOr<size_t> Process::procfs_get_thread_stack(ThreadID thread_id, KBufferBuilder& builder) const
+{
+    JsonArraySerializer array { builder };
+    auto thread = Thread::from_tid(thread_id);
+    if (!thread)
+        return KResult(ESRCH);
+    bool show_kernel_addresses = Process::current()->is_superuser();
+    bool kernel_address_added = false;
+    for (auto address : Processor::capture_stack_trace(*thread, 1024)) {
+        if (!show_kernel_addresses && !Memory::is_user_address(VirtualAddress { address })) {
+            if (kernel_address_added)
+                continue;
+            address = 0xdeadc0de;
+            kernel_address_added = true;
         }
-
-        array.finish();
-        return true;
+        array.add(address);
     }
 
-    NonnullRefPtr<Thread> m_associated_thread;
-};
-
-class ProcFSProcessStacks final : public ProcFSExposedDirectory {
-    // Note: This directory is special, because everything that is created here is dynamic!
-    // This means we don't register anything in the m_components Vector, and every inode
-    // is created in runtime when called to get it
-    // Every ProcFSThreadStack (that represents a thread stack) is created only as a temporary object
-    // therefore, we don't use m_components so when we are done with the ProcFSThreadStack object,
-    // It should be deleted (as soon as possible)
-public:
-    virtual KResult traverse_as_directory(unsigned, Function<bool(FileSystem::DirectoryEntryView const&)>) const override;
-    virtual RefPtr<ProcFSExposedComponent> lookup(StringView name) override;
+    array.finish();
+    return KSuccess;
+}
 
-    static NonnullRefPtr<ProcFSProcessStacks> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        auto directory = adopt_ref(*new (nothrow) ProcFSProcessStacks(parent_directory));
-        return directory;
-    }
+InodeIndex Process::component_index() const
+{
+    return SegmentedProcFSIndex::build_segmented_index_for_pid_directory(pid());
+}
 
-    virtual void prepare_for_deletion() override
-    {
-        ProcFSExposedDirectory::prepare_for_deletion();
-        m_process_directory.clear();
-    }
+NonnullRefPtr<Inode> Process::to_inode(const ProcFS& procfs_instance) const
+{
+    return ProcFSProcessDirectoryInode::create(procfs_instance, m_protected_values.pid);
+}
 
-private:
-    ProcFSProcessStacks(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSExposedDirectory("stacks"sv, parent_directory)
-        , m_process_directory(parent_directory)
-    {
-    }
-    WeakPtr<ProcFSProcessDirectory> m_process_directory;
-    mutable Mutex m_lock;
-};
+KResult Process::traverse_as_directory(unsigned fsid, Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
+{
+    callback({ ".", { fsid, SegmentedProcFSIndex::build_segmented_index_for_pid_directory(pid()) }, 0 });
+    callback({ "..", { fsid, ProcFSComponentRegistry::the().root_directory().component_index() }, 0 });
+    callback({ "fd", { fsid, SegmentedProcFSIndex::build_segmented_index_for_sub_directory(pid(), SegmentedProcFSIndex::ProcessSubDirectory::FileDescriptions) }, 0 });
+    callback({ "stacks", { fsid, SegmentedProcFSIndex::build_segmented_index_for_sub_directory(pid(), SegmentedProcFSIndex::ProcessSubDirectory::Stacks) }, 0 });
+    callback({ "unveil", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(pid(), SegmentedProcFSIndex::MainProcessProperty::Unveil) }, 0 });
+    callback({ "pledge", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(pid(), SegmentedProcFSIndex::MainProcessProperty::Pledge) }, 0 });
+    callback({ "fds", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(pid(), SegmentedProcFSIndex::MainProcessProperty::FileDescriptions) }, 0 });
+    callback({ "exe", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(pid(), SegmentedProcFSIndex::MainProcessProperty::BinaryLink) }, 0 });
+    callback({ "cwd", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(pid(), SegmentedProcFSIndex::MainProcessProperty::CurrentWorkDirectoryLink) }, 0 });
+    callback({ "perf_events", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(pid(), SegmentedProcFSIndex::MainProcessProperty::PerformanceEvents) }, 0 });
+    callback({ "vm", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(pid(), SegmentedProcFSIndex::MainProcessProperty::VirtualMemoryStats) }, 0 });
+    callback({ "root", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(pid(), SegmentedProcFSIndex::MainProcessProperty::RootLink) }, 0 });
+    return KSuccess;
+}
 
-KResult ProcFSProcessStacks::traverse_as_directory(unsigned fsid, Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
+KResult Process::traverse_stacks_directory(unsigned fsid, Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
 {
-    MutexLocker locker(m_lock);
-    auto parent_directory = m_process_directory.strong_ref();
-    if (parent_directory.is_null())
-        return KResult(EINVAL);
-    callback({ ".", { fsid, component_index() }, 0 });
-    callback({ "..", { fsid, parent_directory->component_index() }, 0 });
+    callback({ ".", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property(pid(), SegmentedProcFSIndex::ProcessSubDirectory::Stacks, SegmentedProcFSIndex::MainProcessProperty::Reserved) }, 0 });
+    callback({ "..", { fsid, component_index() }, 0 });
 
-    auto process = parent_directory->associated_process();
-    if (process.is_null())
-        return KResult(ESRCH);
-    process->for_each_thread([&](const Thread& thread) {
+    for_each_thread([&](const Thread& thread) {
         int tid = thread.tid().value();
-        InodeIdentifier identifier = { fsid, thread.global_procfs_inode_index() };
+        InodeIdentifier identifier = { fsid, SegmentedProcFSIndex::build_segmented_index_for_thread_stack(pid(), thread.tid()) };
         callback({ String::number(tid), identifier, 0 });
     });
     return KSuccess;
 }
 
-RefPtr<ProcFSExposedComponent> ProcFSProcessStacks::lookup(StringView name)
+RefPtr<Inode> Process::lookup_stacks_directory(const ProcFS& procfs, StringView name) const
 {
-    MutexLocker locker(m_lock);
-    auto parent_directory = m_process_directory.strong_ref();
-    if (parent_directory.is_null())
-        return nullptr;
-    auto process = parent_directory->associated_process();
-    if (process.is_null())
-        return nullptr;
-    RefPtr<ProcFSThreadStack> procfd_stack;
+    RefPtr<ProcFSProcessPropertyInode> thread_stack_inode;
     // FIXME: Try to exit the loop earlier
-    process->for_each_thread([&](const Thread& thread) {
+    for_each_thread([&](const Thread& thread) {
         int tid = thread.tid().value();
+        VERIFY(!(tid < 0));
         if (name == String::number(tid)) {
-            procfd_stack = ProcFSThreadStack::create(*parent_directory, *this, thread);
+            thread_stack_inode = ProcFSProcessPropertyInode::create_for_thread_stack(procfs, thread.tid(), pid());
         }
     });
-    return procfd_stack;
+    return thread_stack_inode;
 }
 
-class ProcFSProcessFileDescriptions;
-class ProcFSProcessFileDescription final : public ProcFSExposedLink {
-public:
-    // Note: we pass const ProcFSProcessFileDescriptions& just to enforce creation of this in the correct directory.
-    static NonnullRefPtr<ProcFSProcessFileDescription> create(unsigned fd_number, const FileDescription& fd, InodeIndex preallocated_index, const ProcFSProcessFileDescriptions&)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessFileDescription(fd_number, fd, preallocated_index));
-    }
-
-private:
-    explicit ProcFSProcessFileDescription(unsigned fd_number, const FileDescription& fd, InodeIndex preallocated_index)
-        : ProcFSExposedLink(String::formatted("{}", fd_number), preallocated_index)
-        , m_associated_file_description(fd)
-    {
-    }
-    virtual bool acquire_link(KBufferBuilder& builder) override
-    {
-        builder.append_bytes(m_associated_file_description->absolute_path().bytes());
-        return true;
-    }
-
-    NonnullRefPtr<FileDescription> m_associated_file_description;
-};
-
-class ProcFSProcessFileDescriptions final : public ProcFSExposedDirectory {
-    // Note: This directory is special, because everything that is created here is dynamic!
-    // This means we don't register anything in the m_components Vector, and every inode
-    // is created in runtime when called to get it
-    // Every ProcFSProcessFileDescription (that represents a file descriptor) is created only as a temporary object
-    // therefore, we don't use m_components so when we are done with the ProcFSProcessFileDescription object,
-    // It should be deleted (as soon as possible)
-public:
-    virtual KResult traverse_as_directory(unsigned, Function<bool(FileSystem::DirectoryEntryView const&)>) const override;
-    virtual RefPtr<ProcFSExposedComponent> lookup(StringView name) override;
-
-    static NonnullRefPtr<ProcFSProcessFileDescriptions> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessFileDescriptions(parent_directory));
-    }
-
-    virtual void prepare_for_deletion() override
-    {
-        ProcFSExposedDirectory::prepare_for_deletion();
-        m_process_directory.clear();
-    }
-
-private:
-    explicit ProcFSProcessFileDescriptions(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSExposedDirectory("fd"sv, parent_directory)
-        , m_process_directory(parent_directory)
-    {
-    }
-    WeakPtr<ProcFSProcessDirectory> m_process_directory;
-    mutable Mutex m_lock;
-};
+KResultOr<size_t> Process::procfs_get_file_description_link(unsigned fd, KBufferBuilder& builder) const
+{
+    auto file_description = m_fds.file_description(fd);
+    if (!file_description)
+        return EBADF;
+    auto data = file_description->absolute_path();
+    builder.append(data);
+    return data.length();
+}
 
-KResult ProcFSProcessFileDescriptions::traverse_as_directory(unsigned fsid, Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
+KResult Process::traverse_file_descriptions_directory(unsigned fsid, Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
 {
-    MutexLocker locker(m_lock);
-    auto parent_directory = m_process_directory.strong_ref();
-    if (parent_directory.is_null())
-        return KResult(EINVAL);
     callback({ ".", { fsid, component_index() }, 0 });
-    callback({ "..", { fsid, parent_directory->component_index() }, 0 });
-
-    auto process = parent_directory->associated_process();
-    if (process.is_null())
-        return KResult(ESRCH);
+    callback({ "..", { fsid, component_index() }, 0 });
     size_t count = 0;
-    process->fds().enumerate([&](auto& file_description_metadata) {
+    fds().enumerate([&](auto& file_description_metadata) {
         if (!file_description_metadata.is_valid()) {
             count++;
             return;
         }
-        InodeIdentifier identifier = { fsid, file_description_metadata.global_procfs_inode_index() };
+        InodeIdentifier identifier = { fsid, SegmentedProcFSIndex::build_segmented_index_for_file_description(pid(), count) };
         callback({ String::number(count), identifier, 0 });
         count++;
     });
     return KSuccess;
 }
-RefPtr<ProcFSExposedComponent> ProcFSProcessFileDescriptions::lookup(StringView name)
+
+RefPtr<Inode> Process::lookup_file_descriptions_directory(const ProcFS& procfs, StringView name) const
 {
-    MutexLocker locker(m_lock);
-    auto parent_directory = m_process_directory.strong_ref();
-    if (parent_directory.is_null())
-        return nullptr;
-    auto process = parent_directory->associated_process();
-    if (process.is_null())
-        return nullptr;
-    RefPtr<ProcFSProcessFileDescription> procfd_fd;
+    RefPtr<ProcFSProcessPropertyInode> file_description_link;
     // FIXME: Try to exit the loop earlier
     size_t count = 0;
-    process->fds().enumerate([&](auto& file_description_metadata) {
+    fds().enumerate([&](auto& file_description_metadata) {
         if (!file_description_metadata.is_valid()) {
             count++;
             return;
         }
         if (name == String::number(count)) {
-            procfd_fd = ProcFSProcessFileDescription::create(count, *file_description_metadata.description(), file_description_metadata.global_procfs_inode_index(), *this);
+            file_description_link = ProcFSProcessPropertyInode::create_for_file_description_link(procfs, static_cast<unsigned>(count), pid());
         }
         count++;
     });
-    return procfd_fd;
+    return file_description_link;
 }
 
-class ProcFSProcessPledge final : public ProcFSProcessInformation {
-public:
-    static NonnullRefPtr<ProcFSProcessPledge> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessPledge(parent_directory));
-    }
-
-private:
-    explicit ProcFSProcessPledge(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSProcessInformation("pledge"sv, parent_directory)
-    {
-    }
-    virtual bool output(KBufferBuilder& builder) override
-    {
-        auto parent_directory = m_parent_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        JsonObjectSerializer obj { builder };
-#define __ENUMERATE_PLEDGE_PROMISE(x)       \
-    if (process->has_promised(Pledge::x)) { \
-        if (!builder.is_empty())            \
-            builder.append(' ');            \
-        builder.append(#x);                 \
+KResult Process::procfs_get_pledge_stats(KBufferBuilder& builder) const
+{
+    JsonObjectSerializer obj { builder };
+#define __ENUMERATE_PLEDGE_PROMISE(x) \
+    if (has_promised(Pledge::x)) {    \
+        if (!builder.is_empty())      \
+            builder.append(' ');      \
+        builder.append(#x);           \
+    }
+    if (has_promises()) {
+        StringBuilder builder;
+        ENUMERATE_PLEDGE_PROMISES
+        obj.add("promises", builder.build());
     }
-        if (process->has_promises()) {
-            StringBuilder builder;
-            ENUMERATE_PLEDGE_PROMISES
-            obj.add("promises", builder.build());
-        }
 #undef __ENUMERATE_PLEDGE_PROMISE
-        obj.finish();
-        return true;
-    }
-};
-
-class ProcFSProcessUnveil final : public ProcFSProcessInformation {
-public:
-    static NonnullRefPtr<ProcFSProcessUnveil> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessUnveil(parent_directory));
-    }
-
-private:
-    explicit ProcFSProcessUnveil(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSProcessInformation("unveil"sv, parent_directory)
-    {
-    }
-    virtual bool output(KBufferBuilder& builder) override
-    {
-        auto parent_directory = m_parent_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        JsonArraySerializer array { builder };
-        for (auto& unveiled_path : process->unveiled_paths()) {
-            if (!unveiled_path.was_explicitly_unveiled())
-                continue;
-            auto obj = array.add_object();
-            obj.add("path", unveiled_path.path());
-            StringBuilder permissions_builder;
-            if (unveiled_path.permissions() & UnveilAccess::Read)
-                permissions_builder.append('r');
-            if (unveiled_path.permissions() & UnveilAccess::Write)
-                permissions_builder.append('w');
-            if (unveiled_path.permissions() & UnveilAccess::Execute)
-                permissions_builder.append('x');
-            if (unveiled_path.permissions() & UnveilAccess::CreateOrRemove)
-                permissions_builder.append('c');
-            if (unveiled_path.permissions() & UnveilAccess::Browse)
-                permissions_builder.append('b');
-            obj.add("permissions", permissions_builder.to_string());
-        }
-        array.finish();
-        return true;
-    }
-};
-
-class ProcFSProcessPerformanceEvents final : public ProcFSProcessInformation {
-public:
-    static NonnullRefPtr<ProcFSProcessPerformanceEvents> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessPerformanceEvents(parent_directory));
-    }
-
-private:
-    explicit ProcFSProcessPerformanceEvents(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSProcessInformation("perf_events"sv, parent_directory)
-    {
-    }
-    virtual bool output(KBufferBuilder& builder) override
-    {
-        InterruptDisabler disabler;
-        auto parent_directory = m_parent_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        if (!process->perf_events()) {
-            dbgln("ProcFS: No perf events for {}", process->pid());
-            return false;
-        }
-        return process->perf_events()->to_json(builder);
-    }
-};
+    obj.finish();
+    return KSuccess;
+}
 
-class ProcFSProcessOverallFileDescriptions final : public ProcFSProcessInformation {
-public:
-    static NonnullRefPtr<ProcFSProcessOverallFileDescriptions> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessOverallFileDescriptions(parent_directory));
-    }
+KResult Process::procfs_get_unveil_stats(KBufferBuilder& builder) const
+{
+    JsonArraySerializer array { builder };
+    for (auto& unveiled_path : unveiled_paths()) {
+        if (!unveiled_path.was_explicitly_unveiled())
+            continue;
+        auto obj = array.add_object();
+        obj.add("path", unveiled_path.path());
+        StringBuilder permissions_builder;
+        if (unveiled_path.permissions() & UnveilAccess::Read)
+            permissions_builder.append('r');
+        if (unveiled_path.permissions() & UnveilAccess::Write)
+            permissions_builder.append('w');
+        if (unveiled_path.permissions() & UnveilAccess::Execute)
+            permissions_builder.append('x');
+        if (unveiled_path.permissions() & UnveilAccess::CreateOrRemove)
+            permissions_builder.append('c');
+        if (unveiled_path.permissions() & UnveilAccess::Browse)
+            permissions_builder.append('b');
+        obj.add("permissions", permissions_builder.to_string());
+    }
+    array.finish();
+    return KSuccess;
+}
 
-private:
-    explicit ProcFSProcessOverallFileDescriptions(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSProcessInformation("fds"sv, parent_directory)
-    {
+KResult Process::procfs_get_perf_events(KBufferBuilder& builder) const
+{
+    InterruptDisabler disabler;
+    if (!const_cast<Process&>(*this).perf_events()) {
+        dbgln("ProcFS: No perf events for {}", pid());
+        return KResult(ENOBUFS);
     }
-    virtual bool output(KBufferBuilder& builder) override
-    {
-        auto parent_directory = m_parent_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        JsonArraySerializer array { builder };
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        if (process->fds().open_count() == 0) {
-            array.finish();
-            return true;
-        }
-
-        size_t count = 0;
-        process->fds().enumerate([&](auto& file_description_metadata) {
-            if (!file_description_metadata.is_valid()) {
-                count++;
-                return;
-            }
-            bool cloexec = file_description_metadata.flags() & FD_CLOEXEC;
-            RefPtr<FileDescription> description = file_description_metadata.description();
-            auto description_object = array.add_object();
-            description_object.add("fd", count);
-            description_object.add("absolute_path", description->absolute_path());
-            description_object.add("seekable", description->file().is_seekable());
-            description_object.add("class", description->file().class_name());
-            description_object.add("offset", description->offset());
-            description_object.add("cloexec", cloexec);
-            description_object.add("blocking", description->is_blocking());
-            description_object.add("can_read", description->can_read());
-            description_object.add("can_write", description->can_write());
-            count++;
-        });
+    return const_cast<Process&>(*this).perf_events()->to_json(builder) ? KSuccess : KResult(EINVAL);
+}
 
+KResult Process::procfs_get_fds_stats(KBufferBuilder& builder) const
+{
+    JsonArraySerializer array { builder };
+    if (fds().open_count() == 0) {
         array.finish();
-        return true;
-    }
-};
-
-class ProcFSProcessRoot final : public ProcFSExposedLink {
-public:
-    static NonnullRefPtr<ProcFSProcessRoot> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessRoot(parent_directory));
-    }
-
-private:
-    explicit ProcFSProcessRoot(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSExposedLink("root"sv)
-        , m_parent_process_directory(parent_directory)
-    {
-    }
-    virtual bool acquire_link(KBufferBuilder& builder) override
-    {
-        auto parent_directory = m_parent_process_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        builder.append_bytes(process->root_directory_relative_to_global_root().absolute_path().to_byte_buffer());
-        return true;
-    }
-    WeakPtr<ProcFSProcessDirectory> m_parent_process_directory;
-};
-
-class ProcFSProcessVirtualMemory final : public ProcFSProcessInformation {
-public:
-    static NonnullRefPtr<ProcFSProcessRoot> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessVirtualMemory(parent_directory));
+        return KSuccess;
     }
 
-private:
-    explicit ProcFSProcessVirtualMemory(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSProcessInformation("vm"sv, parent_directory)
-    {
-    }
-    virtual bool output(KBufferBuilder& builder) override
-    {
-        auto parent_directory = m_parent_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        JsonArraySerializer array { builder };
-        {
-            ScopedSpinLock lock(process->address_space().get_lock());
-            for (auto& region : process->address_space().regions()) {
-                if (!region->is_user() && !Process::current()->is_superuser())
-                    continue;
-                auto region_object = array.add_object();
-                region_object.add("readable", region->is_readable());
-                region_object.add("writable", region->is_writable());
-                region_object.add("executable", region->is_executable());
-                region_object.add("stack", region->is_stack());
-                region_object.add("shared", region->is_shared());
-                region_object.add("syscall", region->is_syscall_region());
-                region_object.add("purgeable", region->vmobject().is_anonymous());
-                if (region->vmobject().is_anonymous()) {
-                    region_object.add("volatile", static_cast<Memory::AnonymousVMObject const&>(region->vmobject()).is_volatile());
-                }
-                region_object.add("cacheable", region->is_cacheable());
-                region_object.add("address", region->vaddr().get());
-                region_object.add("size", region->size());
-                region_object.add("amount_resident", region->amount_resident());
-                region_object.add("amount_dirty", region->amount_dirty());
-                region_object.add("cow_pages", region->cow_pages());
-                region_object.add("name", region->name());
-                region_object.add("vmobject", region->vmobject().class_name());
-
-                StringBuilder pagemap_builder;
-                for (size_t i = 0; i < region->page_count(); ++i) {
-                    auto* page = region->physical_page(i);
-                    if (!page)
-                        pagemap_builder.append('N');
-                    else if (page->is_shared_zero_page() || page->is_lazy_committed_page())
-                        pagemap_builder.append('Z');
-                    else
-                        pagemap_builder.append('P');
-                }
-                region_object.add("pagemap", pagemap_builder.to_string());
-            }
+    size_t count = 0;
+    fds().enumerate([&](auto& file_description_metadata) {
+        if (!file_description_metadata.is_valid()) {
+            count++;
+            return;
         }
-        array.finish();
-        return true;
-    }
-};
-
-class ProcFSProcessCurrentWorkDirectory final : public ProcFSExposedLink {
-public:
-    static NonnullRefPtr<ProcFSProcessCurrentWorkDirectory> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessCurrentWorkDirectory(parent_directory));
-    }
-
-private:
-    explicit ProcFSProcessCurrentWorkDirectory(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSExposedLink("cwd"sv)
-        , m_parent_process_directory(parent_directory)
-    {
-    }
-    virtual bool acquire_link(KBufferBuilder& builder) override
-    {
-        auto parent_directory = m_parent_process_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        builder.append_bytes(process->current_directory().absolute_path().bytes());
-        return true;
-    }
-
-    WeakPtr<ProcFSProcessDirectory> m_parent_process_directory;
-};
-
-class ProcFSProcessBinary final : public ProcFSExposedLink {
-public:
-    static NonnullRefPtr<ProcFSProcessBinary> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessBinary(parent_directory));
-    }
-
-    virtual mode_t required_mode() const override
-    {
-        auto parent_directory = m_parent_process_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        if (!process->executable())
-            return 0;
-        return ProcFSExposedComponent::required_mode();
-    }
-
-private:
-    explicit ProcFSProcessBinary(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSExposedLink("exe"sv)
-        , m_parent_process_directory(parent_directory)
-    {
-    }
-    virtual bool acquire_link(KBufferBuilder& builder) override
-    {
-        auto parent_directory = m_parent_process_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        auto* custody = process->executable();
-        if (!custody)
-            return false;
-        builder.append(custody->absolute_path().bytes());
-        return true;
-    }
-
-    WeakPtr<ProcFSProcessDirectory> m_parent_process_directory;
-};
+        bool cloexec = file_description_metadata.flags() & FD_CLOEXEC;
+        RefPtr<FileDescription> description = file_description_metadata.description();
+        auto description_object = array.add_object();
+        description_object.add("fd", count);
+        description_object.add("absolute_path", description->absolute_path());
+        description_object.add("seekable", description->file().is_seekable());
+        description_object.add("class", description->file().class_name());
+        description_object.add("offset", description->offset());
+        description_object.add("cloexec", cloexec);
+        description_object.add("blocking", description->is_blocking());
+        description_object.add("can_read", description->can_read());
+        description_object.add("can_write", description->can_write());
+        count++;
+    });
 
-void ProcFSProcessDirectory::on_attach()
-{
-    VERIFY(m_components.size() == 0);
-    m_components.append(ProcFSProcessPledge::create(*this));
-    m_components.append(ProcFSProcessUnveil::create(*this));
-    m_components.append(ProcFSProcessPerformanceEvents::create(*this));
-    m_components.append(ProcFSProcessFileDescriptions::create(*this));
-    m_components.append(ProcFSProcessOverallFileDescriptions::create(*this));
-    m_components.append(ProcFSProcessRoot::create(*this));
-    m_components.append(ProcFSProcessVirtualMemory::create(*this));
-    m_components.append(ProcFSProcessCurrentWorkDirectory::create(*this));
-    m_components.append(ProcFSProcessBinary::create(*this));
-    m_components.append(ProcFSProcessStacks::create(*this));
+    array.finish();
+    return KSuccess;
 }
 
-RefPtr<ProcFSExposedComponent> ProcFSProcessDirectory::lookup(StringView name)
+KResult Process::procfs_get_root_link(KBufferBuilder& builder) const
 {
-    // Note: we need to allocate all sub components when doing a lookup, because
-    // for some reason, the caller may not call ProcFSInode::attach method before calling this.
-    if (m_components.size() == 0)
-        on_attach();
-    return ProcFSExposedDirectory::lookup(name);
+    builder.append_bytes(const_cast<Process&>(*this).root_directory_relative_to_global_root().absolute_path().to_byte_buffer());
+    return KSuccess;
 }
 
-KResult ProcFSProcessDirectory::refresh_data(FileDescription&) const
+KResult Process::procfs_get_virtual_memory_stats(KBufferBuilder& builder) const
 {
-    if (m_components.size() != 0)
-        return KSuccess;
-    const_cast<ProcFSProcessDirectory&>(*this).on_attach();
+    JsonArraySerializer array { builder };
+    {
+        ScopedSpinLock lock(address_space().get_lock());
+        for (auto& region : address_space().regions()) {
+            if (!region->is_user() && !Process::current()->is_superuser())
+                continue;
+            auto region_object = array.add_object();
+            region_object.add("readable", region->is_readable());
+            region_object.add("writable", region->is_writable());
+            region_object.add("executable", region->is_executable());
+            region_object.add("stack", region->is_stack());
+            region_object.add("shared", region->is_shared());
+            region_object.add("syscall", region->is_syscall_region());
+            region_object.add("purgeable", region->vmobject().is_anonymous());
+            if (region->vmobject().is_anonymous()) {
+                region_object.add("volatile", static_cast<Memory::AnonymousVMObject const&>(region->vmobject()).is_volatile());
+            }
+            region_object.add("cacheable", region->is_cacheable());
+            region_object.add("address", region->vaddr().get());
+            region_object.add("size", region->size());
+            region_object.add("amount_resident", region->amount_resident());
+            region_object.add("amount_dirty", region->amount_dirty());
+            region_object.add("cow_pages", region->cow_pages());
+            region_object.add("name", region->name());
+            region_object.add("vmobject", region->vmobject().class_name());
+
+            StringBuilder pagemap_builder;
+            for (size_t i = 0; i < region->page_count(); ++i) {
+                auto* page = region->physical_page(i);
+                if (!page)
+                    pagemap_builder.append('N');
+                else if (page->is_shared_zero_page() || page->is_lazy_committed_page())
+                    pagemap_builder.append('Z');
+                else
+                    pagemap_builder.append('P');
+            }
+            region_object.add("pagemap", pagemap_builder.to_string());
+        }
+    }
+    array.finish();
     return KSuccess;
 }
 
-NonnullRefPtr<ProcFSProcessDirectory> ProcFSProcessDirectory::create(const Process& process)
+KResult Process::procfs_get_current_work_directory_link(KBufferBuilder& builder) const
 {
-    return adopt_ref_if_nonnull(new (nothrow) ProcFSProcessDirectory(process)).release_nonnull();
+    builder.append_bytes(const_cast<Process&>(*this).current_directory().absolute_path().bytes());
+    return KSuccess;
 }
 
-void ProcFSProcessDirectory::prepare_for_deletion()
+mode_t Process::binary_link_required_mode() const
 {
-    ProcFSExposedDirectory::prepare_for_deletion();
-    m_associated_process.clear();
+    if (!executable())
+        return 0;
+    return ProcFSExposedComponent::required_mode();
 }
 
-ProcFSProcessDirectory::ProcFSProcessDirectory(const Process& process)
-    : ProcFSExposedDirectory(String::formatted("{:d}", process.pid().value()), ProcFSComponentRegistry::the().root_directory())
-    , m_associated_process(process)
+KResult Process::procfs_get_binary_link(KBufferBuilder& builder) const
 {
+    auto* custody = executable();
+    if (!custody)
+        return KResult(ENOEXEC);
+    builder.append(custody->absolute_path().bytes());
+    return KSuccess;
 }
 
 }